Electrochemical water splitting cell

Abstract

A CaTiO 3 —TiO 2 composite electrode and method of making is described. The composite electrode comprises a substrate with an average 2-12 μm thick layer of CaTiO 3 —TiO 2 composite particles having average diameters of 0.2-2.2 μm. The method of making the composite electrode involves contacting the substrate with an aerosol comprising a solvent, a calcium complex, and a titanium complex. The CaTiO 3 —TiO 2 composite electrode is capable of being used in a photoelectrochemical cell for water splitting.

The invention claimed is: 
     
       1. An electrochemical water splitting cell, comprising:
 a composite thin film electrode, comprising:
 a transparent conducting substrate, and 
 a CaTiO 3 —TiO 2  layer having an average thickness of 2-12 μm adjacent the transparent conducting substrate, the CaTiO 3 —TiO 2  layer comprising crystalline CaTiO 3 —TiO 2  particles having an average diameter of 0.2-2.2 μm, 
 wherein the CaTiO 3 —TiO 2  layer comprises 25-87 wt % CaTiO 3  and 13-75 wt % TiO 2 , each relative to a total weight of the CaTiO 3 —TiO 2  layer; 
 
 a counter electrode comprising one or more metals or carbon; and 
 an aqueous electrolyte solution in contact with both electrodes. 
 
     
     
       2. The electrochemical water splitting cell of  claim 1 , wherein the CaTiO 3 —TiO 2  layer comprises 80-85 wt % CaTiO 3  and 15-20 wt % TiO 2 , each relative to a total weight of the CaTiO 3 —TiO 2  layer. 
     
     
       3. The electrochemical water splitting cell of  claim 1 , wherein the crystalline CaTiO 3 —TiO 2  particles are substantially spherical. 
     
     
       4. The electrochemical water splitting cell of  claim 1 , wherein the TiO 2  is in anatase phase. 
     
     
       5. The electrochemical water splitting cell of  claim 1 , wherein the composite thin film electrode has a direct band gap value in a range of 2.5-3.5 eV. 
     
     
       6. The electrochemical water splitting cell of  claim 1 , wherein the transparent conducting substrate is selected from the group consisting of ITO, FTO, AZO, GZO, IZO, IZTO, IAZO, IGZO, IGTO, and ATO. 
     
     
       7. The electrochemical water splitting cell of  claim 1 , wherein the transparent conducting substrate has a sheet resistance in a range of 1-40 Ωsq −1 . 
     
     
       8. The electrochemical water splitting cell of  claim 1 , wherein the electrolyte solution comprises water and an inorganic base having a concentration of 0.5-1.5 M. 
     
     
       9. The electrochemical water splitting cell of  claim 1 , wherein the composite thin film electrode has a current density of 0.45-0.8 mA/cm 2  when the electrodes are subjected to a bias potential of 0.6-0.8 V and an illumination of 80-150 mW/cm 2 . 
     
     
       10. The electrochemical water splitting cell of  claim 1 , wherein the composite thin film electrode has a charge transfer resistance in a range of 200-400Ω when subjected to an illumination of 80-150 mW/cm 2 .